1. Field of the Invention
The present invention relates to a rear projector that displays image on a transmissive screen.
2. Description of Related Art
Conventionally, a rear projector that displays a projected and enlarged image on a screen is known as a large-screen display device.
In such rear projector, the light beam from a light source is irradiated on a transmissive liquid crystal panel, where the light beam is modulated in accordance with image information by the transmissive liquid crystal panel, and is enlarged by a projection lens, of which optical path is changed by a reflection mirror to be introduced to a rear side of a screen.
According to the above arrangement, all of the components can be housed in a movable casing and the image on the screen can be viewed in a well-lighted room.
In order to adjust the position of the image displayed on the screen, a position adjuster, which normally adjusts the position of the projection lens in horizontal or vertical position, is necessary for such rear projector. Such mechanism is shown in, for instance, Japanese Patent Laid-Open Publication No. 2001-94905 and Japanese Patent Laid-Open Publication No. 2002-107663.
However, when such simple position adjuster where the position of the projection lens is horizontally or vertically adjusted is used for adjusting the position of the image, there is certain limit capable of adjusting the display position of the image and undisplayable area for displaying the image is formed on the screen even after adjusting the position of the projection lens.
Further, there is difference in the tolerance of the profile of the casing of the rear projector and the tolerance of the component installed in the casing, the tolerance causing difference in aspect ratio of the displayed image, so that the projection dispersion is generated on the image displayed on the screen.
Minute adjustment is required to optimize the projection dispersion. However, since undisplayable area is formed by the conventional divisional display position adjuster, the image cannot be displayed on the entire screen and, when large undisplayable area is formed, the displayed image runs off the edge of the screen and only the image displayed within the frame of the screen can be recognized by a viewer.
An object of the present invention is to provide a rear projector capable of facilitating the position adjustment of the image displayed on the screen and optimizing the projection dispersion of the aspect ratio of the image caused by tolerance of components.
A rear projector according to an aspect of the present invention comprises: an image generator having an electric optical device that modulates a light beam irradiated by a light source and forms an optical image in accordance with image information and a projection optical system that enlarges and projects the optical image; a box-shaped casing that houses the image generator; and a screen exposed on one of the lateral sides of the box-shaped casing onto which the optical image generated by the image generator is projected, the casing having a support plate that supports the image generator, the image generator being mounted on a support base having a support surface inclined relative to the support plate, the support plate being provided with an inclination position adjusting mechanism that adjusts the inclination position of the image generator relative to the support plate.
The support plate may be a component independent of the casing, or may be one of the upper side, lateral side or lower side of the casing.
In the above aspect of the present invention, the support plate is provided on the casing and the image generator is located on the support base having a support surface slanted relative to the support plate, where the inclination position adjusting mechanism is provided on the support base. The attitude of the image generator projecting the generated optical image is adjusted by the inclination position adjusting mechanism. Accordingly, distortion of the image displayed on the screen can be optimized by adjusting the attitude thereof and the undisplayable area of the image projected on the screen can be narrowed in adjusting the position of the image projected and displayed on the screen by the image generator. Accordingly, even when the aspect ratio of the displayed image changes according to difference in tolerance of the configuration of the casing of the rear projector and tolerance of the components installed in the casing and dispersion is caused on the image displayed on the screen, optimization is possible by adjusting the attitude of the image generator by the inclination position adjusting mechanism, thus displaying the image on the entire screen.
Further, since the image generator is disposed on the support base having the support surface inclined relative to the support plate, the dimension of the rear projector in a direction to be away from the screen, i.e. the thickness of the rear projector can be reduced, thus reducing the size of the projector.
In the rear projector according to an aspect of the present invention, the support base may preferably be disposed on the support plate in an inclined manner.
According to the above arrangement, self-weight of the image generator can be securely received by the support base and the support plate, thus securely supporting the image generator in accordance with attitude adjustment of the image generator.
In the rear projector according to an aspect of the present invention, the support base may preferably be disposed on the lower side of the support plate in an inclined manner.
According to the above arrangement, the image generator is located between the support plate and the support base and is isolated in the casing from the other components such as the screen. Therefore, even when heat is generated in the image generator, heat migration to the other components such as the screen can be prevented by circulating cooling air along the support plate and the support base.
In the rear projector according to an aspect of the present invention, a planar position adjusting mechanism that adjusts the planar position of the image generator relative to the screen may preferably be provided on the support base.
According to the above arrangement, the planar position of the image generator relative to the screen surface can be adjusted by providing the planar position adjusting mechanism on the support base, so that the focus or the display position of the image displayed on the screen can be adjusted.
Accordingly, even when the aspect ratio of the displayed image is changed on account of difference in the tolerance of the configuration of the casing of the rear projector and the tolerance of the components installed in the casing so that the image displayed on the screen is located beyond the screen frame, undisplayable area can be narrowed by the planar position adjusting mechanism, thus displaying the image on the entire screen.
In the rear projector according to an aspect of the present invention, the planar position adjusting mechanism may preferably comprise a slide adjuster that adjusts the position of the image generator in a direction along the screen and in normal line direction of the screen.
According to the above arrangement, since the planar position adjusting mechanism has the slide adjuster, the planar position of the image generator can be adjusted by moving the slide adjuster, thus easily adjusting the planar position of the image generator.
In the rear projector according to an aspect of the present invention, a rotary position adjusting mechanism that adjusts rotary position of the image generator relative to the screen may preferably be provided on the support base.
According to the above arrangement, since the support base is provided with the rotary position adjusting mechanism, the rotation of the image generator that projects the optical image can be adjusted, thus optimizing the position shift caused by distortion or rotation of the image displayed on the screen.
In the above arrangement, the rotary position adjusting mechanism may preferably adjust the rotation of the image generator around planar position of the optical axis of the light beam irradiated by the projection optical system.
When the image displayed on the screen is rotated relative to the screen frame, the rotation of the displayed image has to be adjusted. During the rotation adjustment, if the rotation is adjusted when the rotation center of the displayed image is remote from the displayed image, the displayed image is rotated on the screen surface while causing planar movement.
Since the rotary position adjusting mechanism adjusts the rotation of the image generator around the planar position of the optical axis of the light beam irradiated by the projection optical system, the image generator can be rotated around the main optical axis of the irradiated light beam when the rotation of the image generator is adjusted. In other words, the image displayed on the screen can be rotated around the illumination optical axis of the displayed image, thus restraining planar movement of the image displayed on the screen and easily adjusting the rotation of the displayed image.
Accordingly, there is no need for adjusting the planar position of the image generator after adjusting the rotation of the image generator, thereby enhancing working efficiency.
In the rear projector according to an aspect of the present invention, both of the support plate and the support base may preferably be provided with a screwing mechanism extending toward the opposing support plate or the support base, and the inclination position adjusting mechanism may preferably be a screwing component having a first end screwed to the screwing mechanism of the support plate and a second end screwed to the screwing mechanism of the support base.
According to the above arrangement, since the support plate and the support base have the screwing mechanism and the inclination position adjusting mechanism is a screwing component screwed to the screwing mechanism, the inclination of the support base relative to the support plate can be changed with a simple structure. In other words, the inclination of the image generator can be easily adjusted.
In the rear projector according to the above aspect of the present invention, either one of the support plate and the support base may preferably be provided with a screwing mechanism extending toward the opposing support plate or the support base, and the inclination position adjusting mechanism may preferably be provided with a screwing component having one end screwed to the screwing mechanism provided on one of the support plate and the support base and a convex component provided on the other end of the screwing component rotatably fitted to a concave portion formed on the other of the support plate and the support base.
According to the above arrangement, since one of the support plate and the support base has the screwing mechanism and the concave portion is formed on the other of the support plate and the support base, and since the inclination position adjusting mechanism is provided with the screwing component and the convex portion, the plate base can be moved in advancement and retraction position of the screwing direction by advancing and retracting the screwing component relative to the support plate, thus adjusting the inclination position of the image generator.
Further, in an arrangement where the inclination position adjusting mechanism is disposed at a plurality of locations, since the convex portion rotatably fitted to the concave portion formed on the other of the support plate and the support base is provided on the second end of the screwing component, when the screwing component of one of the plurality of inclination position adjusting mechanisms is advanced and retracted, the engagement of the convex portion formed on the second side of the screwing component and the concave portion formed on the bottom side of the casing can be changed, thus adjusting the inclination of the image generator in a torsional direction of the image generator.
In the above, since the inclination position adjusting mechanism, the planar position adjusting mechanism and the rotary position adjusting mechanism are provided on the support base, the inclination position, the planar position and the rotary position of the image generator can be easily adjusted and the influence of the external force applied on the image generator in adjusting the position of the image generator can be mitigated, thus preventing mutual position shift between the respective optical systems in the image generator and obtaining stable projection image having constant aspect ratio.
A rear projector according to another aspect of the present invention comprises: an image generator having an electric optical device that modulates a light beam irradiated by a light source and forms an optical image in accordance with image information and a projection optical system that enlarges and projects the optical image; a box-shaped casing that houses the image generator; a screen exposed on one of the lateral sides of the box-shaped casing onto which the optical image generated by the image generator is projected; and a reflection optical system that is located on the optical path of the light beam irradiated by the projection optical system to reflect the light beam toward the screen, the reflection optical system being attached to the interior of the casing by a first holder holding the upper end and the lower end of the reflection optical system, in which an attitude adjuster that adjusts the position of the optical axis of the reflection optical system in up-shift direction relative to the light beam irradiated by the projection optical system is provided on the first holder on the upper end.
Normally, the casing that houses the image generator, the reflection optical system and the screen is formed by injection molding etc., and slight dimension tolerance is inevitably caused in such casing.
When the reflection optical system such as mirror is fixed to the casing, the mirror is bent on account of the slight dimension tolerance and there is projection dispersion in the images displayed on the screen on account of the change in the aspect ratio of the projected image.
According to the above aspect of the present invention, since the reflection optical system is attached to the interior of the casing by the holder and the attitude adjuster is provided on the holder on the upper end, the up-shift direction of the optical axis of the reflection optical system can be adjusted by adjusting the attitude of the reflection optical system by the attitude adjuster.
Accordingly, even when the aspect ratio of the displayed image is changed on account of the difference in tolerance of the configuration of the casing of the rear projector and the tolerance of the components installed in the casing causing projection dispersion on the image displayed on the screen, optimization is possible by adjusting the attitude of the reflection optical system by the attitude adjuster, thereby displaying the image on the entire screen.
The reflection optical system may preferably be composed of an approximately trapezoidal mirror, which can be arranged in a minimum shape required in accordance with the aspect ratio of the image projected by the image generator, so that the size and weight of the rear projector can be reduced while sufficiently working as the reflection optical system.
In the rear projector according to an aspect of the present invention, the first holder on the upper end may preferably have a groove for an end of the reflection optical system to be inserted, and a gap may preferably be formed between the end of the reflection optical system and the bottom of the groove when the reflection optical system is attached.
According to the above arrangement, since the holder on the upper end has the groove and a gap is formed between the end of the reflection optical system and the bottom of the groove when the reflection optical system is attached, the end of the reflection optical system does not collide with the bottom of the groove of the holder when the attitude of the reflection optical system is adjusted by the attitude adjuster, thereby preventing the external force being locally applied on the end of the reflection optical system.
Accordingly, the attitude of the reflection optical system can be smoothly adjusted by the attitude adjuster and distortion of the reflection optical system by the external force can be avoided by preventing the external force being applied on the end of the reflection optical system, thus mitigating projection dispersion of the image displayed on the screen.
In the rear projector according to an aspect of the present invention, an elastic member may preferably be interposed between a surface of the first holder and the surface of the reflection optical system opposite to the reflection surface thereof.
According to the above arrangement, since the elastic member is interposed between the surface of the first holder and the surface of the reflection optical system opposite to the reflection surface thereof, damage on the end of the reflection optical system caused by friction between the holder and the reflection optical system in accordance with attitude adjustment of the reflection optical system by the attitude adjuster can be mitigated.
Further, by the pressing force of the elastic member, the reflection surface of the reflection optical system is brought into contact with the end of the holder and the attitude of the reflection optical system can be adjusted while keeping the contact there between.
Accordingly, there is no distortion on the reflection optical system by adjusting the attitude of the reflection optical system by the attitude adjuster, thereby accurately maintaining the inclination of the reflection optical system.
In the rear projector according to an aspect of the present invention, the reflection optical system may preferably be attached to the casing by a second holder holding the lateral side of the reflection optical system, and an elastic member may preferably be interposed between a surface of the second holder and the reflection surface of the reflection optical system.
According to the above arrangement, since the reflection optical system is attached to the casing by the second holder holding the lateral side thereof and the elastic member is interposed between a surface of the second holder and the reflection surface of the reflection optical system, the self-weight of the reflection optical system can be supported by the second holder, so that deformation of the reflection optical system caused by self-weight of the reflection optical system such as distortion can be prevented and change in aspect ratio of the image displayed on the screen by the deformation can be avoided, thereby mitigating projection dispersion.
Further, since the elastic member is interposed on a surface of the second holder to be in contact with the reflection optical system, the end of the reflection optical system can be received by the elastic deformation of the elastic member in adjusting the attitude of the reflection optical system by the attitude adjuster.
Accordingly, the end of the reflection optical system can be received by the elastic deformation of the elastic member in accordance with inclination of the reflection optical system, thereby avoiding restriction of the inclination of the reflection optical system by the fixed holder.